Search Publications
NLTE treatment of calcium in the Monte Carlo modeling of early-time spectra of SN 1993J.
Zhang, Q.; Wang, Z. R.
NLTE treatment of calcium with five lower bound energy levels of Ca II and the ionization state of Ca III is annexed to the Monte Carlo model to improve our study on the early-time spectra of SN 1993J. This NLTE + Monte Carlo code is employed in modeling the ultraviolet and optical spectra of SN 1993J obtained simultaneously on 1993 April 15 by th…
Joint ULYSSES and WIND observations of a particle event in April 1995.
Simnett, G. M.; Pick, M.; Bothmer, V. +5 more
In this paper we analyze a solar particle event that was measured at two locations in the heliosphere. Ulysses was at 40°north heliolatitude and 130°west in heliolongitude from Earth while WIND was near Earth at 1 AU in the ecliptic plane. To establish the origin of the particle events, solar coronal activity is investigated. Direct observational …
Absolute magnitudes and kinematics of oxygen Mira variables.
Luri, X.; Figueras, F.; Torra, J. +1 more
A new maximum likelihood method, using apparent magnitudes, proper motions and radial velocities, has been applied to a sample of 90 Mira stars extracted from the HIPPARCOS Input Catalogue (INCA) to determine absolute magnitudes and kinematics. Using this new method three different groups of Mira stars have been identified in the sample, with diff…
Coronal diffusion and high solar latitude recurrent energetic particle increases.
Keppler, E.; Fraenz, M.; Quenby, J. J. +2 more
Ulysses observations have demonstrated that energetic particle flux increases are not only found to be associated with the regularly appearing recurrent fast streams seen at mid solar latitudes but also that they persist with the same periodicity of occurrence to at least 64° latitude, well into the region where no accompanying plasma speed enhanc…
PG 0009+036: a rapidly rotating normal B star in the galactic halo.
de Boer, K. S.; Heber, U.; Moehler, S. +1 more
We present the spectroscopic analysis of a rapidly rotating main sequence B star at high galactic latitude. From optical and ultraviolet spectra of PG 0009+036 we find for the atmospherical parameters T_eff_=14500K, logg=3.9, and a rotational velocity of vsini=320km/s. The effects of rotation on the fundamental parameters of the star are discussed…
Search for neutron star spin periods in X-ray bursts.
van der Klis, M.; Jongert, H. C.
We report a search for pulsations in 147 Type 1 X-ray bursts observed with EXOSAT in 10 X-ray burst sources. Instead of treating each burst separately, we incoherently averaged the power spectra of all of the bursts of a given burster to improve statistics. No periodicities were detected; 99% confidence upper limits on the modulation depths of pos…
HR 4289 - an X-ray luminous galaxy close to the bright star.
Schmitt, J. H. M. M.; Reimers, D.; Huensch, M.
Using new optical, UV and X-ray observations we show that the K5 III star HR 4289, formerly believed to be the only ROSAT All-Sky survey detection to the right of the coronal diving line, should not be identified with the X-ray source. Pointed ROSAT PSPC observations demonstrate that the X-ray source is slightly extended, and locate the X-ray sour…
The apsidal motion in extragalactic stars: the masses of the eclipsing binary HV 2274 in the Large Magellanic Cloud.
Claret, A.
Theoretical apsidal motion rates based on evolutionary stellar models are used to evaluate masses and radii of an extragalactic eclipsing binary (HV 2274) in the Large Magellanic Cloud. As radial velocity curves are not available, from the results of the analysis of the light curve and the detected apsidal motion it was possible to constrain the v…
HST observations of the PG 1159 type central star of K1-16.
Patriarchi, P.; Perinotto, M.
The central star of the planetary nebula K1-16, belonging to the class of the pulsating PG 1159 pre-white dwarfs, has been observed with the HST telescope using the GHRS in the zone of the CIV λ1550A doublet, to ascertain the reality and examine the properties of the exceptionally fast wind suggested to occur in this star by low resolution IUE obs…
An emission line region associated with 3C 273.
Meisenheimer, K.; Hippelein, H.; Roeser, H. J.
We have observed an extended emission line region about 4" to the South-East of 3C 273 in the light of the lines [OII]λ372.8nm and [OIII]λ500.7nm, with an overall linear dimension of ~20x10kpc and a brightness of ~10^-18^W/m^2^ in either line. HST images show the region to be split up into several knots. The line intensity ratios and colors are co…